I believe it is a combination of polygenic inheritance and environmental factors. Several genes control the height in humans, giving an overall normal distribution. Environmental factors on the other hand such as nutrition smooth out the curve. It is therefore important to note that Human height is a quantitative, or metric trait, that is, a characteristic that is measured in quantity, and is controlled by multiple genes and environmental factors.
I would say A.
B and C can be eliminated because they have to do with using resources more efficiently. Now we're down to A and D, and of the two, I'd say A is most plausible. Globalization is the connection of the world with each other. With all this technology, companies see endless possibilities to sell their products. They use more and more natural resources, which can deplete those resources quickly.
We breathe in air, not straight oxygen. Attached is a pie chart showing roughly what percentage of what is in the air we breathe
Plants reduce the carbon dioxide (CO2) in the atmosphere and create more oxygen, which is needed by all organisms, through photosynthesis. :)
